Field of the Invention
The present invention relates to a receiving apparatus.
Description of Related Art
In recent years, receiving apparatuses, such as a television broadcast receiving apparatus and the like, capable of receiving satellite broadcast are widespread. A broadcast signal received by an antenna undergoes frequency conversion performed by a tuner. And the broadcast signal undergoing the frequency conversion performed by the tuner is demodulated by a demodulator.
In more detail, the tuner includes a local oscillator and a filter circuit. The broadcast signal (output signal from the antenna) is multiplied by a local oscillation signal output from the local oscillator and undergoes the frequency conversion to turn into a base band signal. The base band signal goes through the filter circuit to remove an unnecessary component and is output to the demodulator.
In the meantime, some receiving apparatuses include a plurality of tuners and each tuner obtains a broadcast signal. The local oscillator of each tuner includes an oscillation circuit that outputs an oscillation signal and the local oscillation signal is generated based on the oscillation signal output from the oscillation circuit. In this case, there is a case where the oscillation signal output from the oscillation circuit in a tuner and the oscillation signal output from the oscillation circuit in another tuner are multiplied by each other to generate a synthetic signal. There is a problem that the frequency of this synthetic signal falls in a frequency band of a selected channel by one tuner, whereby reception quality deteriorates.